The long-term objective of this collaborative project is to broaden current studies of the persistence of the AIDS virus and other lentiviruses to encompass retroviruses in general, utilizing a biological model developed by Dr. Svoboda. Conventional in situ and other hybridization techniques and new amplification methods will be employed in defining the cellular and anatomic sites of persistence and the relationship of viral gene expression to persistence. Retroviral genomes will also be characterized at the nucleotide sequence level to assess the role of mutation and diversity in establishing and maintaining infection.